Somethings not right

For a while now iv felt like my responses to social situations and how I feel is off. At first I thought it was just a part of being a teenager having explosive emotions and episodes of feeling really down and up and struggling to deal with emotions of sadness, emptiness and anger but now I have reached young adulthood finding that things have only progressed or become more uncontrollable especially with the use of substance abuse. Growing up I had a privileged life and my parents always wanted the best for me but during my teenage years I really struggled with the relationship between my older brother who suffered aspergers. He would often have very explosive arguments with my parents particularly my father which would often turn physical and last hours. I remember listening to them in my room and being scared of my brother, he would often insult and belittle me saying extremely hurtful things that he knew we’re my weaknesses (I knew of his condition but didn’t full understand it) In these difficult times I know my parents were under a lot of pressure and after witnessing his behaviour I would often act out aswell and my father would sometimes become physical with me nothing serious just being smacked or sometimes dragged to the ground. During these teenage years I developed a lot of anger and sadness because of the rocky relationships in my family. I had friends growing up but had a lot of anxiety that these people would leave me especially in romantic relationships. I feel as iv gotten older and not going to school social situations have become even worse I find myself constantly avoiding social situations because I get social anxiety and would rather avoid being in a situation I feel uncomfortable, I often think people have the worst intentions and expect the worse from people as a safe guard to not be disappointed if they do let me down, I worry a lot about what people think of me and have slowly been ruining my long term romantic relationship with my fear of being abandoned which has resulted in a fear of seperation I feel if I’m not around he will realise life is better without me. I often lash out and say hurtful things in my explosive anger and then feel guilty for long periods after that I couldn’t control myself. I have extremely low self confidence although some days I feel good about myself I know in whole I am a ver insecure person. I feel extremely powerless and stressed a lot of the time. I don’t know what to do and how to help myself. My partner tells me I have nothing wrong that I just have bad anxiety but sometimes I feel it may be something more. Has anyone else experienced similar emotions and how have they gone about fixing things? Or does anyone have an advice to offer? It would be greatly appreciated